USP1, an MAPK Target with Chaperone-like Activity, Regulates Innate Plant Immunity in Arabidopsis
- 1Center for Desert Agriculture, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
- 2Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21551, Saudi Arabia
Abstract
In eukaryotes, mitogen-activated protein kinase (MAPK) cascades are highly conserved signaling modules in transducing extracellular signals perceived by receptors/sensors. MAPKs phosphorylate cytoplasmic and nuclear target proteins, modifying their stability, protein–protein interaction, enzyme activity, DNA-binding affinity, and subcellular localization. A comparative phosphoproteomics analysis of wild-type and mapk mutant plants identified a previously uncharacterized protein, USP1, as a novel MAPK target. In this work, we investigated the role of USP1 in pathogen responses. CRISPR-Cas9-generated knockout usp1 mutants displayed enhanced resistance to the bacterial pathogen P. syringae pv. tomato DC3000, reduced apoplast reactive oxygen species (ROS) accumulation, and upregulated defense marker genes such as WRKY29 and FRK1. Transcriptome analyses revealed that immune hormone signaling genes, such as salicylic acid (SA) and jasmonic acid (JA), are differentially regulated. These hormones are responsible for primary defense responses against biotrophic and necrotrophic pathogens, respectively. Accordingly, usp1 mutants show enhanced and reduced resistance to bacterial and fungal infection by Pst DC3000 and Botrytis cinerea, respectively. Biochemical analyses showed that USP1 exhibits chaperone-like activity that stabilizes various proteins, including the MAPKs MPK4 and MPK6. Furthermore, usp1 mutants were defective in flg22-mediated immune priming, indicating that USP1 is required for the establishment of PAMP-induced immune memory. Collectively, our findings identify USP1 as a MAPK-regulated chaperone that plays an important role in coordinating plant immune responses.
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BibTeX
@article{manickam2026usp1,
title = {{USP1, an MAPK Target with Chaperone-like Activity, Regulates Innate Plant Immunity in Arabidopsis}},
author = {Prabhu Manickam and Hanna Alhoraibi and Alaguraj Veluchamy and Marilia Almeida-Trapp and Naganand Rayapuram and Heribert Hirt},
journal = {International Journal of Molecular Sciences},
year = {2026},
month = oct,
doi = {10.3390/ijms27219426},
url = {https://www.mdpi.com/1422-0067/27/21/9426},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - USP1, an MAPK Target with Chaperone-like Activity, Regulates Innate Plant Immunity in Arabidopsis
AU - Prabhu Manickam
AU - Hanna Alhoraibi
AU - Alaguraj Veluchamy
AU - Marilia Almeida-Trapp
AU - Naganand Rayapuram
AU - Heribert Hirt
PY - 2026
DA - 2026/10/22
JO - International Journal of Molecular Sciences
DO - 10.3390/ijms27219426
UR - https://www.mdpi.com/1422-0067/27/21/9426
AB - In eukaryotes, mitogen-activated protein kinase (MAPK) cascades are highly conserved signaling modules in transducing extracellular signals perceived by receptors/sensors. MAPKs phosphorylate cytoplasmic and nuclear target proteins, modifying their stability, protein–protein interaction, enzyme activity, DNA-binding affinity, and subcellular localization. A comparative phosphoproteomics analysis of wild-type and mapk mutant plants identified a previously uncharacterized protein, USP1, as a novel MAPK target. In this work, we investigated the role of USP1 in pathogen responses. CRISPR-Cas9-generated knockout usp1 mutants displayed enhanced resistance to the bacterial pathogen P. syringae pv. tomato DC3000, reduced apoplast reactive oxygen species (ROS) accumulation, and upregulated defense marker genes such as WRKY29 and FRK1. Transcriptome analyses revealed that immune hormone signaling genes, such as salicylic acid (SA) and jasmonic acid (JA), are differentially regulated. These hormones are responsible for primary defense responses against biotrophic and necrotrophic pathogens, respectively. Accordingly, usp1 mutants show enhanced and reduced resistance to bacterial and fungal infection by Pst DC3000 and Botrytis cinerea, respectively. Biochemical analyses showed that USP1 exhibits chaperone-like activity that stabilizes various proteins, including the MAPKs MPK4 and MPK6. Furthermore, usp1 mutants were defective in flg22-mediated immune priming, indicating that USP1 is required for the establishment of PAMP-induced immune memory. Collectively, our findings identify USP1 as a MAPK-regulated chaperone that plays an important role in coordinating plant immune responses.
SN - 1422-0067
ER -